Oracle Forms

Hi all, I want to implement a custom code when the cursor is on a field in Transactions form. I want to begin with something simple. Just pop up a message says "You Have Entered The Description Value"

I have added this code in custom.pll event procedure. I have left everything else as is(default-blank).

form_name varchar2(30) := name_in('SYSTEM.CURRENT_FORM');
block_name varchar2(30) := name_in('SYSTEM.CURSOR_BLOCK');
cursor_item varchar2 (200) := name_in('SYSTEM.CURSOR_ITEM');
record_status varchar2 (200) := name_in('SYSTEM.RECORD_STATUS');
INSTRING varchar2(30) := 'You Have Entered The Description Value';

begin

IF event_name = 'WHEN–NEW–RECORD-INSTANCE' and --is this correct?
form_name='ARXTWMAI' and
block_name = 'TLIN_LINES' and
cursor_item = 'TLIN_LINES.DESCRIPTION'

THEN

FND_MESSAGE.ERASE;
FND_MESSAGE.SET_STRING('TEST');
FND_MESSAGE.SHOW;


END IF;

The form file name is AR_TWMAI.fmb while the header is ARXTWMAI. As you understand I am not getting anything, so I want your advice. It is the first time I use the custom.pll and I am not sure if the above is correct.

Thanks